This study seeks to determine the rate of thromboembolic complications (blood clots), including death attributed to thromboembolic disease, when anticoagulation (blood thinner) therapy is withheld from pregnant patients suspected of deep vein thrombosis (DVT) after a whole-leg compression ultrasound shows no DVT. Patients are followed for three months after the ultrasound to determine if a blood clot is diagnosed during that time.